Monolithic integration of fully ion-implanted lateral GaInAs pin detector/InP JFET amplifier for 1.3-1.55 mu m optical receivers

An optical receiver front-end consisting of a lateral interdigitated GaInAs pin detector integrated with an InP JFET amplifier has been fabricated. This lateral detector structure simplifies the GaInAs material growth requirement to a single layer and provides low capacitance. A quasiplanar approach has been developed in conjunction with a two-level metallisation interconnect scheme. An optical sensitivity of -29 dBm was measured at 560 Mbit/s and 1.3 mu m wavelength.<>     

Proposed scheme for polarization insensitive GaInNAs-based semiconductor optical amplifiers

A novel scheme for polarization insensitive GaInNAs-based semiconductor optical amplifiers is proposed in which TE and TM polarization gain is almost equal for GaInNAs quantum wells with GaInAs barriers. The proposed scheme involves the growth of GaInAs metamorphic layers on GaAs. Based on a k /spl middot/ p Hamiltonian that accounts for the N-induced modifications of the bandstructure, we calculate the optical properties of GaInNAs-GaInAs quantum wells and explore the effect of GaInAs barriers on the valence band mixing effects. The TE and TM amplifier gain of GaInNAs-based semiconductor optical amplifiers with GaInAs barriers is then analyzed.     

GaInAs/GaInAsP strained quantum well monolithic electroabsorption modulator/amplifier by lateral bandgap control with nonplanar substrates

An electroabsorption modulator and an optical amplifier have been monolithically integrated by using nonplanar MOVPE. A bandgap shift of more than 60nm was obtained with atmospheric pressure MOVPE of GaInAs/GaInAsP strained QWs on 10 mu m wide ridges. A chip gain of 9dB and an excitation ratio of 17dB were obtained for the monolithic electroabsorption modulator/amplifier. The integration of an optical amplifier enables the use of a wavelength close to the bandgap of the modulator, resulting in low voltage and low chirp operation.<>     

High-speed monolithic GaInAs pinFET

A monolithic planar structure pin photodiode/field-effect transistor (pinFET) consisting of a low capacitance InP/GaInAs embedded pin photodiode and an AlInAs/GaInAs FET has been developed for long wavelength optical communications. Very high bitrate response capability of over 8 Gbit/s and good receiver performance at 2 Gbit/s have both been demonstrated     

Two‐terminal metal‐inter‐connected multijunction III–V solar cells

A novel bonding approach with an interface consisting of a metal and dielectric is developed, and a “pillar‐array” metal topology is proposed for minimal optical and electrical loss at the interface. This enables a fully lattice‐matched two‐terminal, four‐junction device that consists of an inverted top two‐junction (2J) cell with 1.85 eV GaInP/1.42 eV GaAs, and an upright lower 2J cell with ~1 eV GaInAsP/0.74 eV GaInAs aimed for concentrator applications. The fabrication process and simulation of the metal topology are discussed along with the results of GaAs/GaInAs 2J and (GaInP + GaAs)/GaInAs three‐junction bonded cells. Bonding‐related issues are also addressed along with optical coupling across the bonding interface. Copyright © 2014 John Wiley & Sons, Ltd.     

p-i-n/f.e.t. hybrid optical receiver for longer-wavelength optical communication systems

Preliminary results are reported on the first GaInAs p-i-n/f.e.t. hybrid optical receiver for longer-wavelength optical communication systems. The GaInAs photodiode has a capacitance of 0.3 pF and quantum efficiency of 25%, and gives a receiver sensitivity for a 140 Mbit/s n.r.z. system at 1.24 ?m of ?40.7 dBm for a 10?9 error rate.     

Switching operation in OMVPE grown GaInAs/InP MQW intersectionaloptical switch structures

An intersectional optical switch structure with an intersecting angle of 6° was fabricated on an organometallic vapor-phase epitaxy (OMVPE) grown GaInAs/InP multiple quantum-well (MQW) layered wafer. Switching operation using field-induced refractive index variation was successfully demonstrated at the reverse bias voltage of 8 V for the 1.6 μm wavelength region. Based on this switching, the field-induced refractive index variation in the QW was estimated as around 1%     

GaInAs metal/semiconductor/metal photodetectors with Fe:InP barrier layers grown by chemical beam epitaxy

A GaInAs metal/semiconductor/metal (MSM) photodetector with a dark current less than 1 mu A is described. An Fe-doped InP layer was introduced between the metal and the GaInAs absorbing layer to improve the Schottky barrier height. A breakdown voltage of 30 V was achieved. A DC quantum efficiency of 64% and an impulse response, 1/e fall time of 190 ps were measured for a 20 mu m*100 mu m device. The layer structure is very attractive for integration with high-performance GaInAs/InP FETs.<>     

1 GHz GaInAs:Fe photoconductive optical AND gate with approximately 100 fJ switching energy for time-division access fibre networks

A high-speed, three-port optical AND gate based on GaInAs:Fe photoconductive switches operating at lambda =1.3 mu m is demonstrated. An electrical power contrast ratio of 12 dB is obtained in optical-to-electrical time-division demultiplexing of a 1 GHz signal bit sequence by a 333.3 MHz clock with optical pulse energies of 100 fJ.<>     

10 GHz bandwidth low-noise optical receiver using discrete commercial devices

An ultra-broadband optical receiver using discrete, commercial devices is described. The design comprises a GaInAs PIN detector followed by a three-stage, high-impedance amplifier employing HEMTs interconnected by impedance-matching networks. All devices are mounted on a standard soft substrate. The measured 3 dB bandwidth is nearly 10 GHz, and receiver noise does not exceed 13 pA/ square root (Hz).<>     

Development of high-quantum-efficiency,lattice-mismatched, 1.0-eV GaInAs solar cells

High-quantum-efficiency, lattice-mismatched, 1.0-eV GaInAs solar cells grown by organometallic vapor phase epitaxy have been developed for ultimate integration into AlGaAs/GaAs/GaInAs 3-junction, 2-terminal monolithic devices. The more standard n/p junction was replaced with an n-i-p structure in the GaInAs cell in order to increase the short-circuit current by overcoming the material deficiencies which arise as a result of accommodating the lattice mismatch. This led to single junction 1.0-eV GaInAs cells with internal quantum efficiencies >90% and short-circuit-current densities that match or closely approach those needed to current match the upper AlGaAs and GaAs cells. A 4.1% (1-sun, air mass 0,25°C) power conversion efficiency was achieved with a developmental structure, indicating the potential of the lattice-mismatched n-i-p 1.0-eV GaInAs cell. An analogous device designed to allow direct monolithic integration with the upper AlGaAs and GaAs cells, with a modified grading layer of AlGaInAs in place of the usual GaInAs, achieved an efficiency of 2.2%, primarily due to a lower open-circuit voltage. The open-circuit voltage is perhaps limited by structural defects revealed in transmission electron micrographs.     

Monolithic GaInAs/InP photodetector arrays for high-densitywavelength division multiplexing (HDWDM)

Monolithic arrays of interdigitated GaInAs/InP photodetectors have been fabricated for high density wavelength division multiplexing (HDWDM) applications. The detectors typically exhibit a reverse leakage current of 400 nA, capacitance of less than 70 fF and a responsivity of 0.5 A/W at -5 V bias. An optical crosstalk of -33.4 dB has been measured between adjacent detectors in an experimental grating demultiplexer system. Preliminary electrical crosstalk measurements in the frequency range of 1-500 MHz indicate signal isolation of the order of 46 dB     

High-performance Al/sub 0.48/In/sub 0.52/As/Ga/sub 0.47/In/sub 0.53/As MSM-HEMT receiver OEIC grown by MOCVD on patterned InP substrates

Reports the first demonstration of a new long-wavelength receiver OEIC comprising an AlInAs/GaInAs MSM detector and an AlInAs/GaInAs HEMT preamplifier. The layer structure was grown by LP-MOCVD on patterned InP substrates, which allowed independent optimisation of the MSM detector and HEMT preamplifier. The MSM detector showed the lowest leakage current yet reported and the HEMT exhibited a transconductance of 260 mS/mm. An excellent receiver response to 1.7 Gbit/s NRZ signals has been obtained.<>     

Excess noise design of InP/GaInAsP/GaInAs avalanche photodiodes

An InP/GaInAsP/GaInAs avalanche photodiode (APD) with separate absorption and multiplication (SAM) regions has been designed taking into account the excess noise generated in GaInAsP and GaInAs. The multiplication factor dependence of the excess noise factorFhas been calculated using realistic electron and hole ionization rates in InP, GaInAsP, and GaInAs, assuming that the avalanche multiplication occurs not only in InP but in GaInAsP and GaInAs. The calculatedFvalues have been compared to the experimental ones measured on a planar-type InP/GaInAsP/GaInAs APD for illumination at a wavelength of 1.3 μm. It has been found the the calculated excess noise agrees very well with the experimental measurements. The limited ranges of device parameters in which the conditions of minimal excess noise, tunneling current, and charge pile-up are satisfied have been obtained. We conclude that the excess noise generated in GaInAsP and GaInAs should be considered in a practical device design.     

Gain and phase recovery of optically excited semiconductor optical amplifiers

An investigation of the recovery dynamics of semiconductor optical amplifiers (SOAs) explains why the ultrafast component of the gain recovery is largely absent in the phase response. The time-resolved gain and phase dynamics of a bulk GaInAs SOA are measured using a pump-probe technique and differences between the gain and phase recoveries are highlighted and explained using Kramers-Kronig analysis. These have important implications for optical signal processing.     

-70 dBm APD optical feedback receiver at 2.048 Mbit/s

Demonstrate an optical feedback (OFB) transimpedance receiver employing a GaInAs avalanche photodiode (APD) input device and an Si pin diode feedback element. The highest reported sensitivity of -70 dBm at 2.048 Mbit/s was achieved     

A high-speed eight-channel optoelectronic integrated receiver arraycomprising GaInAs p-i-n PD's and AlInAs/GaInAs HEMTs

The successful fabrication of an eight-channel optoelectronic integrated receiver array on an InP substrate, which comprises eighty elements including GaInAs p-i-n photodiodes (PDs) and AlInAs/GaInAs HEMTs, is reported. An average bandwidth of 1.2 GHz with a standard deviation of 190 MHz over the whole channel was obtained. An average responsivity was 546 V/W with a standard deviation of only 19.2 V/W. A crosstalk was less than -30 dB at frequencies between 3 and 900 MHz and as small as -28 dB even at 1 GHz. The yield of chips available for 1.0 Gb/s operation was as high as 62.5% over 2-in-diameter wafer     

50-nm self-aligned-gate pseudomorphic AlInAs/GaInAs high electronmobility transistors

The design and fabrication of a class of 50-nm self-aligned-gate pseudomorphic AlInAs/GaInAs high electron mobility transistors (HEMTs) with potential for ultra-high-frequency and ultra-low-noise applications are reported. These devices exhibit an extrinsic transconductance of 1740 mS/mm and an extrinsic current-gain cutoff frequency of 340 GHz at room temperature. The small-signal characteristics of a pseudomorphic and a lattice-matched AlInAs/GaInAs HEMT with similar gate length (50 nm) and gate-to-channel separation (17.5 nm) are compared. The former demonstrates a 16% higher transconductance and a 15% higher current-gain cutoff frequency, but exhibits a 38% poorer output conductance. An analysis of the high-field transport properties of ultra-short gate-length AlInAs/GaInAs HEMTs shows that a reduction of gate length from 150 to 50 nm neither enhances nor reduces their average velocity. In contrast, the addition of indium from 53% to 80% improves this parameter by 19%     

GaInAs/InP quantum wires grown by metalorganic vapor phase epitaxy on V-grooved InP substrates

A single nominally lattice matched GaInAs quantum well (QW)/quantum wire (QWR) structure was grown by metalorganic vapor phase epitaxy (MOVPE) in V-grooved InP substrates. Different Si0₂ etch masks with opening widths from 2 μm down to 200 nm (for application as second order DFB grating) were defined by optical and electron beam lithography. A damage-reduced wet chemical etching process enables the growth of the GaInAs QWs/QWRs without any InP buffer layer. In low temperature photoluminescence we found improved intensity for all wire structures prepared by this etching technique. A reduction of the period and opening width of the V-groove etch mask resulted in a optimized luminescence intensity ratio between QW and QWR. Decay times from time resolved luminescence measurements were compared to the decay times of wet or dry etched mesa wires before and after regrowth. The good optical properties of the GaInAs QWRs are encouraging for future application as a QWR-laser device.     

Low threshold current density 1.5 mu m GaInAs/AlGaInAs graded-index separate-confinement-heterostructure quantum well laser diodes grown by metal organic chemical vapour deposition

A low threshold current density of 640 A/cm/sup 2/ was obtained in a 1.5 Gmm GaInAs/AlGaInAs multiple quantum well laser diode, grown by metal organic chemical vapour deposition, with continuously graded-index separate-confinement heterostructure. An internal waveguide loss of 14 cm/sup -1/ and internal quantum efficiency of 59% were obtained, which are comparable to those of GaInAs/GaInAsP quantum well laser diodes.<>